Organic peroxides, and process of preparing the same



April 26, 1938. N. A. MILAS I 2,115,207

ORGANIC PEROXIDES AND PROCESS OF PREPARING THE SAME Original Filed A ril 5, 1935 IN V EN TOR.

wmwawa,

ATTORNEYS.

Patented Apr. 26, 1938 UNITED STATES ORGANIC PEROXIDES, AND PROCESS PREPARING THE SAME Nicholas A. Milas, Belmont, Mass.

Original application April 5, 1935, Serial No.

'14,787. Divided and this application July 22,

1937, SerialNo. 155,062

Claims.

This invention relates to a process of producing organic peroxides and to the resulting products, and the present application is a division of my copending application Serial No. 14,787, filed April 5, 1935. 7

Although auto-oxidation is a well known and well recognized process, the end products thereof vary considerably in both chemical and physical characteristics, such auto-oxidation processes usually producing relatively non-reactive organic substances such as acids, aldehydes, ketones, etc. During the course of such auto-oxidation relatively unstable, highly reactive intermediate substances form, but under ordinary conditions these substances decompose rapidly; the amount present at any time during the process is very small and their isolation is relatively difllcult. In the majority of auto-oxidation processes,

Although some workers have isolated the intermediate products of a few selected auto-oxidation reactions, they invariably used methods which involved refrigeration of the reaction mix- 30 ture, and/or complete removal from the reactants of substances capable of'reacting with or ac celerating the decompositio'n of peroxides. Such processes are of limited applicability and can only I be applied to substances such as aldehydes which 35 readily undergo auto-oxidation even under ordinary conditionsi The auto-oxidation of alcohols is extremely sl'ow' under ordinary conditions as is shown by the fact thatvarious alcohols remained substanio tially unchanged when in contact with air or oxygen for long periods of time. Hence, the

rate of formation of the intermediate peroxides is very slow. Moreover, although their rate of decomposition is also slow, it is apparently as 4:, fast as, or faster than, their rate of formation,

since the concentration of peroxides found under these ordinary conditions is negligible. However,

I have found that the rate of formation of peroxides during the auto-oxidation of alcohols is 50 considerably accelerated by ultra-violet. lights,

while the rate of decomposition of these products is only slightly affected Since, under the joint influence of ultraviolet.

knowledge of the presence of the intermediate products is based merely on theoretical considucts are stable and can be easily isolated or obtained in relatively pure concentrates.

As previously pointed out, auto-oxidation under ordinary conditions occurs to such a slight extent that it is practically impossible to detect either such reactions. or any products of such reactions, but as I am able greatly toincrease the rate of formation of the peroxide without appreciably increasing its rate of decomposition I am able to produce substances which were heretofore unknown and which could not possibly be produced by any process heretofore known. Moreover, as the rate of decomposition of peroxidic products is relatively slow, the concentrated solutions and also the relatively pure substances are stable over moderate lengths of time, and, in fact, far more so than many of the stable organic peroxides now known.

Alcohol peroxides produced in accordance with the present invention are of value for all purposes for which the heretofore known peroxy compounds are now used, for example, germicides (both contact and vapor), fungicides, oxidizing agents, hemostats, etc., and by reason of.

their stability are of much greater value and utility.-

The auto-oxidation of alcohols in accordance with the present invention differs from and is a .marked advance over prior processes in that norefrigeration or other means of preventing the decomposition of the peroxides is required; in fact it is often advantageous, when carrying out the process, to employ temperatures above normal room temperature. Further advantages will be apparent from a consideration of the following description and the accompanying drawing,

wherein p The figure is' a diagrammatic representation of an apparatus suitable for carrying out,

the auto-oxidationof alcohols in accordance with the present invention. v

The term alcohol ashereinafter used designates that class of organic compounds containing one or more hydroxyl groups and which may be designated by such formulae as t H: H R1 I I etc., wherein R, R1, R2, etc. represent different organic radicals.

In accordance with the present invention, the alcohol to be. treated is subjected. to ultra-violet irradiation in the presence of oxygen, air, or other oxygen-containing gas, the reaction preferably being carried out in a quartz vessel such as a flask, coil or the like. The time required to carry out the process may vary from a few minutesto several hours, or even days, depending upon the particular nature of the alcohol in the residue may be separated by precipitation or fractionation under low pressures.

The auto-oxidation of a typical alcohol, for exalkyhqene pemxldes) s y ifi g $935115, to

ample, an alcohol having the general formula 2? i tnmers e m e o owmg m W 6" if 10 R C 0H XR-G -CR- (I) RC wherein R represents the organic radical, proceeds, in all probability, substantially as follows:

wherein (I) may be dimeric, as: R( 0H+Oz-- R -0H.O| 15 R-C /CR n-c =0+m0| or trimeric, as; a RC\ +H,0 R- 0OH It'/O----O\ll1' H BFC v /C-R As a result of the ultra-violet irradiation in the 0 0 presence of free oxygen, there is first obtained a reaction mixture in which there is a high degree of active oxygen as determined by titration, using acidified potassium iodide and standard thiosul- R R fate solution. The initial peroxide formed in the and so reaction mixture, being a derivative of the alco- The presence of the hydroxy peroxides' and hol hydroperoxides'is shown by the benzidene reacfi: tion of Woker, hereinafter referred too as the Woke! reaction, (Woker, Zeit. Allg. Phsiol. 16, 340 is a peroxide of that alcohol and conforms m an (l914) Ber. 4'7, 1024 (1914) whereas that of the probability to the general formula alkylidene peroxides is established by a quantiv tative analysis in accordance with the usual procedures for the identification of organic com- R(IJOOFOH pounds.

The final reaction products in the mixture To Separate the allfylidene Peroxide f comprise alphahydroxy alkyl hydropemxldes other products, I subJect the final reaction mix havingthe general formula ture to vacuum distillation at or below room tem- H peratures, thereby retaining it in the residue.

5 With secondary butyl alcohol (which is illustrative of a typical alcohol) the auto-oxidation H proceeds, in all probability, as follows:

I? III I /O Y 0H,c-0H+0, (1)o11,-c :-00-oH (Iv)0mc +H,0 cm- H, CHI-CH: cam-on, 0

OH CH;O=0

b +1100Ha 11 H=-000H CHr- H:

' I, CHr-CH;

R I CHaC-O'-OCC-H:+Hz0

CHr-CH: CHI-CH3 reacted upon. At the end of the process the unoxidized alcohol, the solvent or volatile medium, as the case may be, may be removed by vacuum distillation at low temperatures, and the peroxide alpha alpha di'nyaroxy dialkyl peroxides, having the general formula respectively.

It is well known that peroxides of the type During the reaction a certain amount of the liberated hydrogen peroxide breaks down to produce water and as a result excess ketone is" 60 formed. This ketone may combine with the alpha hydroxy alkyl hydroperoxide to yield alpha dihydroxy, dialkyl peroxide, as shown in the following equation:

The initial peroxide (I) conforms, in all probability, t6 the formula CH:(|)-0OOH Cfix- 75 which may be expressed more generally'by the formula wherein R and R. are organic radicals. Two of the final reaction products in the mixture, as identified by the Woker reaction, comprise (11) an alpha hydroxy alkyi hydrope'roxlde, having the formula I on onriLo'on CH:- Hi

and (III) an alpha dihydroxy dialkyl peroxide, having the formula.

Another of the final products comprises (Iv) an alkylidene peroxide or its polymer, having the formulas CHr-CH! respectively. These peroxides may be isolated by subjecting the mixture to a high vacuum distillation when .(II) and (III) are more volatile than (IV) which remains in the residue. 7

I .have found that traces of water have a marked effect upon the rate of peroxide formation; accordingly, ity isadvisable that each alcohol be thoroughly dried. I have also found that the relative rates of peroxide formation during the irradiated auto-oxidation of impure alcohols do not necessarily'conform to the relative rates of peroxidation of the same pure substances.

Furthermore, it is highly desirable, if not es-'- sential for satisfactory yields, that the alcohol drol, etc., it may be necessary to dissolve them in a low boiling point solvent which is resistant to peroxidation.

In the figure I have shown an apparatus particularlysuitable for carrying out the autooxidation' of alcohols in accordance with the present invention, it being understood that various other types of apparatus may be used, such, for example, as a quartz flask disposed within a chamber containing an ultra-violet light, in which case the alcohol is exposedin a static system to an atmosphere of oxygen usually-in a large excess. The partlcular'apparatus herein shown comprises a quartz coil circumposed about a Uviarc (ultra-violet) light 5 which is approximately six inches in length. A cylindrical.

reflector or shield 8 is disposed about the coil 5 and this shield is provided with openings 9 and I0 adjacent to its top and bottom edges, respectively, through which the ends of the coil extend.

The lower or inlet end .ll of the coil is connected preferably by a ground joint to one branch l2 of a T, another branch ll of the T being connected to a U-tube or trap l5, and the -lower a tube 21 which leads to the inlet duct 28 of the vessel 25. The top of the vessel is sealed by a plug 30 having a vertically extending bore in which the lower end of an air condenser 32 tightly fits. The top of the condenser 32 is sealed by a plug 34 from which is suspended a thermometer '35 whichextends downwardly into the vessel so that its bulb is at approximately the same level of the normal level of fluid therein. A vent pipe 31 leads oil the condenser 32 and is connected to a moisture trap, here shown as a tube 38, containing calcium chloride. v The delivery tube 18 is connected to a chain of drying tubes 39 which are connected to a suitable oxygen supply, here shown as a tank 40 of compressed oxygen gas, the usual valve ll being provided to control the flow of gas through the delivery tube l8. If desired, a fan may be employed to circulate cool air about the light 6 and thus prevent overheating of the alcohol being auto-oxidized.

The various connections between the diflferent parts of the apparatus should, of course, be leak proof and where such connections are not formed integral with the tubes, per se, (as by fusing the ends of glass tubing) or where ground joints are introduced into the coil 5 either through the delivery tube l8 or the vessel 25, the particular amount varying with the type of alcohol. The are light 6 may then be struck and the valve 4| regulated so that a steady stream of dry oxygen is passed through the delivery tube l8 and into the coil 5. The rate of the flow of the oxygen through the alcohol within the coil is preferably of the order of 1.5 liters per hour, although a greater or less amount may be used. The small bubbles of oxygen passing through the coil 5 and into the vessel 25 and then-out through the vent 31 are not only effective'to keep the alcohol c0n-. stantly agitated but also to maintain a steady the alcohol with oxygen. Any alcohol which volatilizesls condensed by the condenser 32andis into coil 5. 7 ing the reaction may be determined by the thermometer 35 and the particular temperature 1;;.

. returned to the vessel 25 where it is carried back "I,

The temperature of the alcohol durproximately 13.5

sired may be maintained by varying the mined by titrati'ng the samples withdrawn during the period of reaction. When the reaction has been carried to the desired point the irradiated product may be withdrawn from the apparatus, cooled and either stored for later use or distilled under vacuum to produce a concentrated solution, or a residue which, if desired, may be mixed with a suitable inert diluent before use.

The following examples are illustrative of the invention:

Example 1.-Isopropanol.125 cc. o1 isopropanol having a boiling point of 81.9-82.0 0., was irradiated, as above described, for a period oi aphours, the room'temperature being 22 C. and that of the alcohol 40 to 45 C. At the end of the period the irradiation product was analyzed, as above described, and found to contain 0.60% active oxygen, corresponding to 2.8% alkylidene peroxide.

Example 2.Secondary butanoL-l25 cc. of secondary butanol, having a boiling point of 995 0., was irradiated, as above described, fora period of approximately 13 hours, the temperature of the alcohol and that of the room being 41 to 45 0. and 20 0., respectively. Analysis of the irradiated product showed 1.07% active oxygem corresponding to 5.9% alkylidene peroxide.

Example 3.--Normal butanl.120cc. of nor.- mal butanol, having a boiling'point 05117.6 to

- 117.8" 0., was irradiated for a period of 19 hours,

the temperature of the alcohol and that '01 the room being 40 to 43 0.-and 22" 0., respectively.

Analysis of the irradiated product'showed 0.042%

active oxygen, corresponding to 0.25% alkylidene peroxide.

Example 4.-Tertiar1l butanol.-125 cc. of tertiary butanol, having a melting point oi! 25.3 0*." and a boiling point of 82.3 to 82.5" 0., was irradiated for a period of 48 hours, the temperature of the alcohol and that of the room being 42 to 45 C. and22 0., respectively. Analysis of the irradiated product showed 0.068% .active oxygen, corresponding to 0.45% alcohol peroxide (ROaI-I).

Example 5.-Isoamul alcohol.-120 cc.'oi isoamyl' alcohol, having a boiling point of 130.1 to

130.4 0., was irradiated for a period of 23 hours,

the temperature of thealcohol and that of the room being 40 to 44 0., and 20 0., respectively.

Analysis of the irradiated product showed 0.035% active oxygen, corresponding to 0.23%alkylidene peroxide.

Example 6.--Tertiarp amyl alcohol.-120 cc. of tertiary amyl alcohol, having a boiling point of 101.8 to 102.0 0., was irradiated for a period-of 32 hours, the temperature of the alcohol and that of the room being 40 to 45 and'22- 0., respectively. Analysis of the irradiated product showed 0.090% active oxygen, corresponding-to 0.67% aicohol peroxide (R05 1) Example 7.--Seconclaryamyl alcoh0l.-125 (K of secondary amyl alcohol, having a boiling point of 119.0 to 1l 9.5 0., was'irradiated for a period of 20 hours, the temperature of the alcohol and that of the room being 38 to 42 0. and 20 0., respectively. Analysis of the irradiated product showed 0.02% active oxygen, corresponding to 0.14% alkylidene peroxide.

Example 8.--Cyclohexanol.-'1his alcohol was first purified by extracting it with saturated sodium-bisulfite until no more cyclohexanone was removed. It was then carefully dried, first with sodium sulfate and then with lime, after which it was fractionated, and the fraction boiling at 160.0 to 160.5 C. was removed and treated with 2% aqueous permanganate until no further reduction ensued. The cyclohexanol was then dried again over lime and refractionated. 116 cc. of the treated cyclohexanol was then irradiated for a period of 26 hours, the temperature of the alcohol and that of the room being 42 to 48 0. and 22 0., respectively. Analysis of the irradiated product showed 1.62% active oxygen, corresponding to 11.5% alkylidene peroxide.

Example 9.Benzyl alcoh0l.-120 'cc. of benzyl alcohol having a boiling point of 204.5 to 205.0 0., was irradiated for a period of 23.5 hours, the temperature of the alcohol and that of the rooin being 42 to 46 0. and 22 0., respectively. Analysis of the irradiated product showed 0.58% active oxygen, corresponding to 4.5% alkylidene peroxide. v

Example 10.-Phenylethyl alcohol.120 cc. of phenylethyl alcohol, having a boiling point of 202 to 203 0., was irradiated for a period of 18 hours, the'temperature oi the alcohol and that of the room being 39 to 45 C. and 20 0., respectively. Analysis of the irradiated product showed 0.16% active oxygen, corresponding to 1.2% alkylidene peroxide. Example 12.-Triphe1ml carbinoZ.-A quantity of triphenyl carbinol, having a melting point of 162.0 0., was first dissolved in tertiary amyl alcohol and the solution was irradiated for a period of 25 hours, the temperature of the alcohol and that of the room being 42 to 46 C. and 22 0., respectively. Analysis showed 0.035% active oxygen, corresponding to 1.1% alcohol peroxide (ROaH) in the irradiated triphenyl carbinol, these figures being derived by subtracting the calculated or estimated tertiary amyl alcohol peroxide from the total peroxide to give that due to the triphenyl carbinol peroxide.

Example 13.-Benzhydrol.-A quantity of benzhydrol having a melting point of 67.4 C. was first dissolved in tertiary amyl alcohol, as in Example 12, and the solution was irradiated for a period of 19 hours, the temperature of the alcohol and that of the room being 40 to 0. and 20 C., respectively. Analysis showed 0.15% active oxygen, corresponding to 0.85% alkylidene peroxide in the irradiated benzh drol, these figures likewise being obtained as in Example 12.

Example 14.-Methanol.100 cc. or methanol/ within the flask. The temperature of both the atmosphere and alcohol under irradiation was maintained at 50 C. Analysis of the irradiated normal propanol was subjected to irradiation for a period of 80 hours and under the same conditions as set forth in'Examples 14 and 15. Analysis of the irradiated product showed 0.30% active oxygen, corresponding to 1.4% alkylidene peroxide.

Example 17.-Mnoethyl ether of ethylene glycol-120 cc. of monoethyl ether of ethylene glycol was subjectedto irradiation for a period of 15.5 hours, the temperature of the alcohol and that of the room being 44 to 48 C. and 21 C., respectively. Analysis showed 0.43% active oxygen, corresponding to 2.8% alkylidene peroxide.

Miscellaneous alcohoZs.-Further applications of my process to various other alcohols have likewise produced relatively stable peroxides. The treatment of furfuryl alcohol (a primary heterocyclic alcohol), dodecyl' alcohol (a further example of a primary aliphatic alcohol), menr-hol (a typical alcohol of the terpene series), and ethylene glycol (a typical polyhydric alcohol), in accordance with the above procedures has in each case produced peroxides having appreciable amounts of peroxidic products, thus affording a further confirmation of the fact that my process is applicable to alcohols as a class.

In each of the preceding examples the irradiation product was also tested for stability at 0 C. and at 20 to 23 C., and in all cases the peroxide was found to be relatively stable at these temperatures for moderate lengths of time. The structure of the irradiated product may be determined in the manner shown in the following examples, which illustrate the procedure as applied to difierent types of representative alcohols:

Example 18. -A sample of isopropano'l which has been irradiated for fourteen hours and contained 0.50% active oxygen was evaporated, first on a water pump and then overnight on an oil pump, producing a viscous residue. A weighted amount of this residue was transferredto a flask, then hydrolyzed with dilute sulfuric acid and the mixture distilled into a solution of 2-4 dinitrophenyl hydrazine in hydrochloric acid. The precipitate formed was washed, dried and recrystallized. The recrystallized precipitate showed a melting point of 126.5 to 127 C. against a melting point of 128 C. for acetone 2-4 dinitrophenyl h'ydrazone. Before recrystallization the precipitate was weighed and the amount of acetone formed was determined and found to be 77.5 against a theoretical of 78.4% for Cal-I602. Another portion of the residue was weighed into a flask and analyzed for active oxygen. The analysis showed 21.25% active oxygen against a theoretical of 21.6 for CzHsOz, thus, proving the presence of the alkylidene peroxide of acetone. The presence of isopropyl hydroxy hydroperox ide was shown by Wokers reaction.

Example 19.A sample of the peroxide of secondary butyl alcohol was treated and tested in a manner similar to that described in Example 18 and an analysis of the residue showed 78% of methyl ethyl ketone against a theoretical of 81.8 for C4HsO2, and 17.71% active oxygen against a theoretical of 18.18% for C4H8O2, thus proving the presence of the alkylidene peroxide. The presence of alpha hydroxy alkyl peroxide was shown by a. strong reaction with benzidene (Woker's reagent).

Example 20.-A sample of isoamylv alcohol which hadbeen irradiated for twenty-five hours and contained 0.04% active oxygen was evaporated first on a water pump and then on an oil being necessary to remove all the solvent. A

portion of the residue was weighed into a small flask and hydrolyzed with dilute sulfuric acid and the product was then distilled into a solution of 2-4 dinitro-phenyl hydrazine in hydrochloric acid. The precipitate was washed, dried and pump, nearly a week of continuous evacuation recrystallized. -The recrystallized precipitate showed a melting point of 122m 122.4 C. against a melting point of 123 C. for isovaleraldehyde 2-4 dinitro-phenyl hydrazone. The precipitate was weighed before purification and an ,amount of isovaleraldehyde formed fwas determined and found to be 82.4% against a theoretical of 84.6%

for C5H11O2.

Another portion of the residue was weighed into a flask and analyzed for active oxygen. The analysis showed 14.2% active oxygen against a theoretical of 15.4 for CsHnOz, thus showing the presence of the alkylidene peroxide of isovaleraldehyde. In this case, as before, the original solution gave a positive Wokers reaction, show ing the presence of a hydroxy hydroperoxide.

Example 21.-A sample of cyclohexanol which had been irradiated for twenty-six hours and contained 1.62% active oxygen was diluted with three times its volume of dry petroleum ether; and 5 grams of silica gel were then added. The solution was allowed to stand for one week with frequent shakings. A slow adsorption took place, and at the end of this time 21% of the peroxide had been adsorbed. The gel was then filtered off, washed with petroleum ether to remove ad-' hering cyclohexanol, and extracted with cold chloroform. The chloroform solution was evaporated as before and the residue was hydrolyzed with dilute sulfuric acid, after which 2,4 dinitrophenyl hydrazine solution was added. The precipitate was then washed, dried and recrystallized. The melting point of the recrystallized precipitate was found to be 158 C. against 160 .C. for c'yclohexanone 2,4' dinitro-phenyl hydrazone. The amount of cyclohexanone formed was determined, as before, and found to be 85.8 against a theoretical of 86.2 for Cal-11102.

The presence of active oxygen in the residue was determined as before and found to be 14.2 against a theoretical of 15.4 for CsHuOz, thus showing the presence of alkylidene peroxide of cyclohexanone.

I claim:

1. The process of producing peroxides, which comprises causing the auto-oxidation of secondary butyl alcohol by ultra-violet irradiations 'of the relatively pure secondary butyl alcohol substantially free from water.

2. Stable peroxides produced by the auto-oxidation of secondary butyl alcohol during the ir- 3. An alkyl hydroxy hydroperoxide derived 5. A peroxlderof secondary butyl alcohol hav- 7 ing the probable formula.

from secondary butyl alcohol and having the probable formula. v

Y on n om-o-onr-om 5 NICHOLAS A. MILAS. 

